Epihalohydrin cure regulators

ABSTRACT

A process for controlling premature curing of epihalohydrin polymers comprising heating an epihalohydrin homopolymer or a copolymer of epihalohydrin with a compound selected from the group consisting of sulfenamides of imidazolidones, phthalimides and hydantoins.

[451 Aug. 5, 1975 1 1 EPIHALOHYDRIN CURE REGULATORS [75] Inventor: Michael A. Fath, Burton, Ohio [73] Assignee: The Goodyear Tire & Rubber Company, Akron, Ohio [22] Filed: Feb. 13, 1974 [21} App]. No.: 442,035

Related US. Application Data [63] Continuation-impart of Ser. No. 413,127, Novv 5,

[52] U.S. Cl 260/79; 260/2 A [51 Int. Cl. ..C08G 65/32; C08J 3/24 [58] Field of Search...260/2 A, 79, 79.5 NV. 79.5 A, 260/795 13 [56] References Cited UNITED STATES PATENTS 3,057,832 10/1962 Brock 260/79 3,177,182 4/1965 Cottle et a1. 260/795 3,341,491 9/1967 Robinson et a1 260/4575 3,427,319 2/1969 Coran et al. 260/3092 3,473,667 10/1969 COran et al. 260/3097 3,513,139 5/1970 Coran et 211.... 260/795 3,546,185 12/1970 COran et a1. 260/795 3,562,225 2/1971 Coran et a1. 260/795 3,586,696 6/1971 Kerwood et a1. 260/326 3,640,976 2/1972 Boustany 260/795 B 3,717,592 2/1973 Rave 260/2 A Primary Examiner-Melvin Goldstein Assistant Examiner-E. A. Nielsen Attorney, Agent, or Firm-F. W. Brunner; C. R. Schupbach; J. M. Wallace, Jr.

[ 5 7 ABSTRACT A process for controlling premature curing of epihalohydrin polymers comprising heating an epihalohydrin homopolymer or a copolymer of epihalohydrin with a compound selected from the group consisting of sulfenamides of imidazolidones, phthalimides and hydantoins.

7 Claims, No Drawings 1 EPIHALOHYDRIN CURE REGULATORS This is a continuation-in-part application of application Ser. No. 413,127 filed Nov. 5, 1973.

This invention relates to a process for cure regulation of epihalohydrin polymers including homopolymers and copolymers.

The polymers based on epihalohydrins are saturated, high molecular weight, aliphatic polyethers having halomethyl sidechains. The halogen most commonly used is chlorine, although bromine is also known, The copolymer form generally utilizes ethylene oxide in the copolymerization. Epihalohydrins can be cured with materials that react difunctionally with the halomethyl sidechains. Representative examples of such curing materials are diamines, ureas, thioureas and ammonium salts.

A problem commonly encountered during the processing of epihalohydrin rubbers is scorch. Scorch is defined as the premature curing of the polymer. Scorch is undesirable because it prevents or interferes with further processing. It is therefore desirable that rubber additives be used which reduce scorching. Such compounds are commonly referred to as eureregulators or retarders.

The process of this invention comprises mixing a combination of the epihalohydrin polymer and a curing agent described above with from about 0.5 part to about 7.0 parts by weight per 100 parts by weight based on the polymer, preferably from about 1.5 to about 4.5 parts by weight per 100 parts by weight based on the polymer, of an organic material selected from imidazolidones, phthalimides and hydantoins and curing the resulting composition by heating. The materials used as cure regulators are selected from the group consisting of (l) imidazolidones having the general structural formula (11) phthalimides having the general structural formula and (Ill) hydantoins having the general structural formula In the above formulas R, R R, R R", R", R, R", R and R are the same or different radicals selected from the group consisting of alkyl radicals having from 1 to 8 carbon atoms, cycloalkyl radicals having from 5 to 8 carbon atoms, and wherein R and R R and R*, R and R, R and R R and R can be joined through a member of the group consisting of CH O and S to constitute with the attached nitrogen a heterocyclic ring such as morpholino or piperidino.

Representative examples of alkyl groups in the above formulas are ethyl, methyl, isopropyl and n-butyl. Examples of cycloalkyl radicals are cyclohexyl, cycloheptyl and cyclooctyl.

The cure regulators can be compounded or mixed with the polymer using internal mixers such as Banbury mixers or by mill mixing. vulcanization is achieved by heating the resulting mixture at a temperature in the range of from about C. to about 260 C. Generally a temperature in the range from about C. to about 200 C. is used. Curing time will vary from about one minute to about 240 minutes. Usually the time required for curing is from about 10 minutes to about 60 minutes.

Representative examples of cure regulators of the present invention are given by group below.

Group 1 lmidazolidones Group 11 Phthalimides' N-(dieyclohexylaminothio) phthalimide N-(diisopropylaminothio) phthalimide N-( piperidinothio) phthalimide N-(morpholinothio) phthalimide Group 111 Hydantoins 1,3 bis(morpholinothio-5,S-dimethyl hydantoin 1,3 bis(dibutylaminothio)-5,S-dimethyl hydantoin In addition to the cure regulating agents, the polymer composition can contain other compounding materials such as additives and reinforcing materials which are normally used with vulcanized rubber products. Representative examples of such additives are metal oxides, reinforcing agents, pigments, fillers, softening agents, antioxidants, plasticizing agents, etc. The oxides of the Group 11 metals of the Periodic Table increase the degree of cure in a given vulcanization time, and the vulcanized products have a light color valuable in certain uses. Representative examples of such metal oxides are zinc oxide and cadmium oxide.

The invention is described in the working examples given below in which parts and percentages are by weight unless otherwise indicated.

In experiments (1-13) mixing was effected with a two-paddle, water cooled, size B laboratory Banbury. All experimental compounds were mixed using the following procedure. The Banbury was charged with epichlorohydrin polymer, carbon black, stabilizers, process aids and plasticizers. The ram was lowered and the batch was mixed 3 /2 minutes at 50 revolutions per minute (rpm) rotor speed. At 3V2 minutes the ram was raised and the Banbury throat was swept down. The ram was then lowered and the batch was mixed for an additional two minutes. The batch was discharged at a temperature between 125 C. and C. The batch was sheeted out on a two roll mill to a gauge of 0.075

inch and allowed to rest for between 24 and 48 hours.

The curing agents and cure regulators were added on a two roll mill. The compound was sheeted to approximately 0.020 inch with the mill roll temperature at ap- 4 1,3-bis (diisopropylaminothio)-2-imidazolidone 1.3-bis (piperidinothio)-2-imidazolidone 1,3-bis (di-n-butylaminothio)-2-imidazolidone 4 5 l\l-(dicyclohexylaminothio)-phthalimide proximately 100 C. Ethylene thiourea and cure regula- 5 6 N-(diisopropylaminothio)-phthalimidc tors were added. The batch was cross cut 5 times, 7 N-( piperidinothio)-phthalimide rolled off the mill and passed endwise through the mill 8 1,3-bis (morpholinothio)-5,5-dimethylhydantoin bite three times. The batch was then sheeted off the 9 salicyclic acid mill rolls at 0.050 gauge and allowed to rest for be- 10 benzoic acid tween 24 and 48 hours before curing at 160 C. 10 1 1 phthalic anhydride The curing characteristics were determined at 160 12 N-nitroso diphcnylamine C. with an oscillating disc rheometer (manufactured by 13 N-cyclohexylthio phthalimide Monsanto). The rheometer recorded the torque ex- Table] erted on the 3.8 cm. diameter rotor which oscillated 100 times per minute and oscillated with an angle of 5 15 Pans over a predetermined duration of time. Hydfin 200 1000 Curing characteristics as measured with the oscillatcarbon black (FEF) 50.0 ing disc rheometer described above were measured as P P I Sorbrtan monostearate 2.0 to carbon black blends comprising ep1chlorohydr1n- Dibasic lead phthulme ethylene oxide copolymer (Hydrin 200 produced by Dibusic Phosphite Goodrich Chemicals Corn an The f l t' Ethylene th'mma L5 p y a 15 Experimental retarder 6.25 X 10" moles shown in Table 1 below. The carbon black used was FEF type. Dioctyl phthalate, sorbitan monostearate, dibasic lead phthalate, dibasic lead phosphite and eth- The blended imidazolidones and their respective ylene thiourea curative were used as the balance of the quantities are shown in Table 11. The data in Table II system. The compounds of this invention were added show that vulcanizing systems of this invention exhibit and compared to prior art compounds as described besufficiently long induction periods and achieve high delow. Compounds 1 through 8 are the compounds of this grees of vulcanization. Cure times for compositions invention while compounds 9 through 13 are the prior containing the various materials were established by art compounds. the crosslinked density (T values in minutes as deterln Tables 1 through 1V below, the experimental commined by the Monsanto Rheometer previously depounds are identified using the following designations: scribed.

Table 11 Mooney Scorch at 270 F. 132C.)

Min 44 39 37 38 34 43 44 T 2.7 11.5 9.4 11.0 10.5 5.3 6.1

v Max. 91 84 86 91 x5 79 80 Vmin. 19 15 14 15 14 l6 l6 TA2 3.2 5.0 3.9 5.1 4.8 3.6 4.0 T,,,,% 45 2 47 40 55 Stress-Strain Properties (Cure T at 160 C.) Tensile(Mn/M 11.1 13.2 12.6 15.2 11.3 12.5 13.2 /1 Elongation 230 360 320 310 290 335 320 100% Modulus 5.9 4.5 4.8 5.6 4.4 4.4 4.5 Shore A Hard. 72 71 71 66 69 70 68 0 none 1 1,3-bis (morpholinothio)-2-imidazolidone Table 111 below shows the effect of phthalimides much as Table 11 shows the result of imidazolidones.

Table III Mooney Scorch at 270 F.

Min 44 40 39 39 44 50 T 2.7 5.9 5.5 6.6 3.7 3.5 Rheometer at 320 F.

V Max 91 9O 90 88 87 V Min 19 16 15 15 16 19 T 71 50 48 48 45 5O 50 Stress-Strain (Cure T at C.) Tcnsi1c(Mn/M'-') 11.1 12.7 12.5 13.6 11.5 12.0 "/1 Elongation 230 275 270 300 250 265 10071 Modulus 5.9 5.5 5.3 5.3 5.5 5.3 Shore A Hard. 72 73 69 70 73 73 Table IV shows the effect of hydantoin as compared to the prior art compounds.

As'Tab'le V shows, prior art regulators either reduce the state of cure (numbers 6 and 7) or have little effect Table IV 0 8 9 10 l 1 l2 l3 Mooney Scorch at 270 F.

Min 44- 39 44 50 43 44 T 2.7 10.0 3.5 3.7 3.5 5.3 6.1 Rheometer at 320 F.

V Max. 91 80 92 88 87 79 80 V Minv 19 14 19 16 19 16 16 T,,.,7r 50 50 50 50 5O 55 Stress-Strain (Cure T,,;, at 160 C.) Tensile(Mn/M 11.1 13.6 11.8 11.5 12.0 12.5 13.2 7: Elongation 230 370 230 250 265 335 320 100% Modulus 5.9 4.5 6.0 5.5 5.3 4.4 4.5 Shore A Hard. 72 73 73 73 70 68 The above data demonstrate that the regulating agents of this invention are capable of providing a long induction period and achieving a high degree of vulcanization. This allows more effective use of this polymer in applications requiring long induction periods.

The imidazolidone materials all improve scorch behavior, shorten cure time and improve tensile strengths. Scorch control effectiveness at equal molar levels of substituted imidazolidones is: morpholino pipe ridino dibutyl diisopropyl control.

Phthalimides also increased initial tensile and elongation properties. However, relative to imidazolidones, scorch was impaired. Phthalimide scorch control is in the order: piperidino dicyclohexyl diisopropyl control.

The hydantoins produce a high state of cure as well as impart excellent scorch protection.

The polymer compositions prepared by curing using the compounds of this invention can be used in products such as tires. molded goods and industrial rubber products such as transmission belts and hose, especially 45 high temperature hose WhlCh must contain flexibility.

Table V on scorch (numbers ll, 13 and 14) and are therefore not desirable. In contrast, materials of this invention improve scorch delay with a minimal loss in state of cure. Examination of the data from numbers 2, 8, 9 and 10 indicates even a higher state of cure and excellent scorch delay in ethylene thiourea cured polymers containing no sulfur.

While certain representative embodiments and details have been shown for the purpose of illustrating the invention. it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing from the spirit or the scope of the invention.

1 claim:

1. A process for the curing of an epihalohydrin polymer selected from the group consisting of (A) epihalohydrin homopolymers, and (B) epihalohydrin-ethylene oxide copolymers, comprising mixing epihalohydrin homopolymer or copolymer with difunctional curing agents which react with the halomethyl side chains of the polymer while in the presence of from about 0.5 to about 7.0 parts by weight based on the polymer of an Cure Regulators in Hydrin 100 and Hydrin 200 Rank as Scorch Time Max. Rheometer Scorch at 270 F. Torque During Inhibitor Min.) Cure (in.-lb.)

Material 100 200 100 200 100 200 1,3-bis(morpholinothio)Q-imiduzolidonc l 1 1 1.0 1 1.5 79 84 l.3-his(piperidinothio 2-imidazolidone 2 2 10.6 1 1.0 92 91 1.3-bis1dihutylaminothio)-2-imidazolidone 3 3 9.7 10.5 88 85 l .3-his( (1iisupropylaminothio )-2-imidazolidone 4 5 8.8 9.4 87 86 l.3-bis( morpholinolhio )-5.5-dimcthylhydantoin 5 4 8.7 10.0 80 80 N-nitroso diphcnylamine 6 10 7.0 5.3 72 79 N-cyclohexylthiophthalimide (PVl) 7 7 6.2 6.1 N-( dicyclohexylaminothio )-phthulimide 8 8 6.0 5.9 91 90 N-( piperidinothio )-phthalimide 9 6 5.6 6.6 97 90 N-( diisopropylaminothio )-phthalimide l0 9 5.5 5.5 93 90 phthalic unhydridc 1 1 13 4.4 3.5 83 87 control nothing added 12 14 4.3 2.7 84 91 salicyclic acid l3 12 4.1 3.4 81 92 henzoic acid 14 1 l 3.8 3.7 79 88 organic material selected from the group consisting of (l) imidazolidones having the general structural formula wherein R R", R andR are thesame or different radicals selected from the. group consisting of alkyl raddantoin is icals having from l to 8 carbon atoms, cycloalkyl radicals having from 5 to 8 carbon atoms and wherein R and R", and R and R can bejoined through a member of the group consisting of Cl-l O and -S- to constitute with the attached nitrogen a heterocyclic ring and heating the mixture formed at a temperature of from about 130 C. to about 200 C. for a time sufficient for curing to take place.

2. A process as described in claim 1 wherein the imidazolidones are selected from the group consisting of l ,3-bis( morpholinothio-2-imidazolidone; Y l,3- bis( diisopropylaminothio )-2-imidazolidone; l ,3 bis(piperidinothio)-2-imidazolidone and l,3-bis(di-nbutylaminothio)-2-imidazolidone.

3. A process as described in claim 1 wherei n the byl ,3-bis( morpholinothio-S ,S-dimethyl hydantoin; I '2 4. A process as described in claim 1 wherein the epihalohydrin polymer is an epichlorohydrin homopolymer.

5. A process as described in claim 1 wherein the epihalohydrin polymer is a copolymer of epichlorohydrin and ethylene oxide.

6. A process as described in claim 1 wherein the organic material is presentfrom l .5 to 4.5 parts by weight per 100 parts by weight of the polymer,

' 7. A process as described in claim 1 wherein the cure regulators are usedwith metal oxides selected from the group-consisting of zinc oxide and cadmium oxide. 

1. A PROCESS FOR CURING AN EPIHALOHYDRIN POLYMER SELECTED FROM THE GROUP CONSISTING OF (A) EPIHALOHYDRIN HOMONOLYMERS, AND (B) EPIHALOHYDRIN-ETHYLENE OXIDE COPOLYMERS, COMPRISING MIXING EPIHALOHYDRIN HOMOPOLYMER OR COPOLYMER WITH DIFUNCTIONAL CURING AGENTS WHICH REACT WITH THE HALOMETYL SIDE CHAINS OF TH POLYMER WHILE IN THE PRESENCE OF FROM ABOUT 0.5 ABOUT 7.0PARTS BY WEIGHT BASED ON THE POLYMER OF AN ORGANIC MATERIAL SELECTED FROM THE GROUP CONSISTING OF (1) IMIDAZOLIDONES HAVING THE GENERAL STRUCTURAL FORMULA
 2. A process as described in claim 1 wherein the imidazolidones are selected from the group consisting of 1,3-bis(morpholinothio-2-imidazolidone; 1,3-bis(diisopropylaminothio)-2-imidazolidone; 1,3-bis(piperidinothio)-2-imidazolidone and 1,3-bis(di-n-butylaminothio)-2-imidazolidone.
 3. A process as described in claim 1 wherein the hydantoin is 1, 3-bis(morpholinothio-5,5-dimethyl)-hydantoin.
 4. A process as described in claim 1 wherein the epihalohydrin polymer is an epichlorohydrin homopolymer.
 5. A process as described in claim 1 wherein the epihalohydrin polymer is a copolymer of epichlorohydrin and ethylene oxide.
 6. A process as described in claim 1 wherein the organic material is present from 1.5 to 4.5 parts by weight per 100 parts by weight of the polymer.
 7. A process as described in claim 1 wherein the cure regulators are used with metal oxides selected from tHe group consisting of zinc oxide and cadmium oxide. 